The easiest and most reliable joining method is the mechanical joint with a bolt and nut or rivet. However, in the case of composite laminates, mechanical joint properties decrease because of lower interlaminar proper...The easiest and most reliable joining method is the mechanical joint with a bolt and nut or rivet. However, in the case of composite laminates, mechanical joint properties decrease because of lower interlaminar properties compared to in-plane properties around hole.?This study investigated needle punching process with the aim of improving the mechanical properties in the thickness direction of fiber-reinforced plastic composite laminates with an open hole. Needle punching process was applied to glass fiber chopped strand matused as the reinforcement for the composite laminates. Open-hole tensile tests and observations of end cross-sections after the tests were performed. The tensile properties and fracture mechanism of the specimens subjected to needle punching process were investigated. In addition, characteristic distance (a parameter for evaluating resistance to fracture in open-hole tensile test specimens) was also calculated to examine the effects of needle punching process conditions on fracture toughness. Tensile strength was improved by more than 15% by needle punching process. However, when a certain needle punching density was exceeded, the mechanical properties worsened. In addition, characteristic distance increased with increasing needle punching density. Thus, these results suggest that there is an optimal needle punching density with respect to strength and characteristic distance.展开更多
Objective:To explore the efficacy and potential mechanisms of the ethanol extract of Abelmoschus manihot(L.)Medic in contrast-induced nephropathy(CIN).Methods:CIN rat models and human renal proximal tubular cells(HK-2...Objective:To explore the efficacy and potential mechanisms of the ethanol extract of Abelmoschus manihot(L.)Medic in contrast-induced nephropathy(CIN).Methods:CIN rat models and human renal proximal tubular cells(HK-2)with iopromide-induced injury were employed to mimic CIN conditions.The effect of Abelmoschus manihot extract on the rat models and HK-2 cells was evaluated.In rat models,kidney function,histology,oxidative stress and apoptosis were determined.In HK-2 cells,cell viability,apoptosis,mitochondrial membrane potential,and endoplasmic reticulum stress were assessed.Results:Abelmoschus manihot extract significantly improved structural and functional impairments in the kidneys of CIN rats.Additionally,the extract effectively mitigated the decline in cellular viability and reduced iopromide-induced oxidative stress and lipid peroxidation.Mechanistic investigations revealed that Abelmoschus manihot extract prominently attenuated acute endoplasmic reticulum stress-mediated apoptosis by downregulating GRP78 and CHOP protein levels.Conclusions:Abelmoschus manihot extract can be used as a promising therapeutic and preventive agent in the treatment of CIN.展开更多
文摘The easiest and most reliable joining method is the mechanical joint with a bolt and nut or rivet. However, in the case of composite laminates, mechanical joint properties decrease because of lower interlaminar properties compared to in-plane properties around hole.?This study investigated needle punching process with the aim of improving the mechanical properties in the thickness direction of fiber-reinforced plastic composite laminates with an open hole. Needle punching process was applied to glass fiber chopped strand matused as the reinforcement for the composite laminates. Open-hole tensile tests and observations of end cross-sections after the tests were performed. The tensile properties and fracture mechanism of the specimens subjected to needle punching process were investigated. In addition, characteristic distance (a parameter for evaluating resistance to fracture in open-hole tensile test specimens) was also calculated to examine the effects of needle punching process conditions on fracture toughness. Tensile strength was improved by more than 15% by needle punching process. However, when a certain needle punching density was exceeded, the mechanical properties worsened. In addition, characteristic distance increased with increasing needle punching density. Thus, these results suggest that there is an optimal needle punching density with respect to strength and characteristic distance.
基金supported by the National Natural Science Foundation of China(No.81973762).
文摘Objective:To explore the efficacy and potential mechanisms of the ethanol extract of Abelmoschus manihot(L.)Medic in contrast-induced nephropathy(CIN).Methods:CIN rat models and human renal proximal tubular cells(HK-2)with iopromide-induced injury were employed to mimic CIN conditions.The effect of Abelmoschus manihot extract on the rat models and HK-2 cells was evaluated.In rat models,kidney function,histology,oxidative stress and apoptosis were determined.In HK-2 cells,cell viability,apoptosis,mitochondrial membrane potential,and endoplasmic reticulum stress were assessed.Results:Abelmoschus manihot extract significantly improved structural and functional impairments in the kidneys of CIN rats.Additionally,the extract effectively mitigated the decline in cellular viability and reduced iopromide-induced oxidative stress and lipid peroxidation.Mechanistic investigations revealed that Abelmoschus manihot extract prominently attenuated acute endoplasmic reticulum stress-mediated apoptosis by downregulating GRP78 and CHOP protein levels.Conclusions:Abelmoschus manihot extract can be used as a promising therapeutic and preventive agent in the treatment of CIN.
